SMTP Error (554): failed to add recipient ... (5.7.1 <email@example.com>: Sender address rejected: Access denied)."
While I can login into my firstname.lastname@example.org account, I CANNOT send any e-mail message, nor from my IMAP desktop e-mail client (which is Vivaldi Browser, BTW(!)), nor from the web interface "webmail.vivaldi.net".
When I press "Send" in the web interface on webmail.vivaldi.net, a red pop-up window appears, saying: "SMTP Error (554): failed to add recipient "email@example.com" (5.7.1 firstname.lastname@example.org: Sender address rejected: Access denied)."
How is it possible that my own access to vivaldi SMTP server is denied, while I am logged in, into webmail.vivaldi.net?(!)
Why can't I send e-mail messages, anymore?
Can anybody help me?
@newscpq Are you trying to use an alias?
@Ayespy no, I'm not